The present invention relates to a photosensitive mixture that contains a photosensitive compound and a polymeric binder which is insoluble in water and soluble or swellable in aqueous-alkaline solutions, and that is especially suitable for producing printed circuits, using the resist technique, and lithographic printing plates for offset printing.
Mixtures of this general type are known from German Offenlegungsschrift No. 2,053,363. They contain, as binders, reaction products of a polymer containing hydroxyl or amino groups and at least one saturated alkyl-, alkoxy-, aryl- or aryloxysulfonyl isocyanate. The binder is processed in combination with diazonium salt condensation products or photopolymerizable mixtures to form photosensitive layers. The mixtures obtained in this way can be developed under aqueous-alkaline conditions only if the binders used have high acid numbers, as a result of which the abrasion resistance and the printing properties of the cured layer are adversely influenced.
Similar mixtures are described in German Offenlegungsschrift No. 2,053,364. They contain reaction products of polymers containing hydroxyl or amino groups and unsaturated sulfonyl isocyanates, an initiator and, optionally, other polymerizable compounds. Reaction products of the same type in combination with diazonium salt polycondensates or low-molecular azides are described in German Offenlegungsschrift No. 3,036,077.
A disadvantage of these mixtures is the complicated and expensive production of the necessary alkenylsulfonyl isocyanates. Moreover, the printing plates produced from these mixtures exhibit an inadequate ink receptivity, so that an unacceptably high output of waste paper is produced during the proofing process and after a prolonged stoppage.